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PREFACE:
T he art of rigging may be traced to prehistoric times. Levers were used then, as now, to pry stones, roll logs, and move objects that were too heavy to be moved by hand. The inclined plane, or natural ramp, was in use even then to help move heavy objects up to higher elevations.
The first major rigging job, of which there is not only a record, but also indisputable evidence, was the construction of the three pyramids at Gizeh, near Cairo, Egypt—about 2700 BC. Estimates are that preparation work must have taken about 10 years, and construction about 20 years. As it stands today, the large pyramid—built to contain the remains of Pharaoh Cheops (Khufu)—is 746 ft (227 m) square at the base and 451 ft (141 m) high. Originally, the structure was encased in fine grain limestone. But at some unknown time during the past 4600 years, or more, this sheath was removed. The large pyramid contains about 2.3 million stones—weighing from 2 to 30 tons each; a total of about 5.75 million tons—nearly 20 times the weight of the masonry in the 102-story Empire State Building in New York City. Inclined Planes (Ramps) Records indicate that a sand ramp, requiring nearly one million tons of sand, transported from the desert, was built-up on one side as the pyramid rose in height.
Another million tons of sand were then required to backfill the interior of the pyramid. And, when the job was completed, the ramp had to be removed. The construction crews had no mechanical equipment. Instead, they used levers, rollers, crude ropes, sledges, plumb lines, and string sightings to get the massive job done.
The huge stones were hauled up the ramp on rollers, for an average lift of 100 ft, by the brute strength of 100,000 slaves in teams of 50 workers each, driven by the slave master’s whips. The pyramid remains today as indisputable proof of the ingenuity and brutality of the Egyptian constructors.
Archaeological records show that as far back as 515 BC, the ancient Greeks were using a crane mechanism for lifting heavy loads using small construction teams—unlike the more labor intensive ramp, requiring large bodies of unskilled labor that had been the norm in the autocratic society of Egypt and Assyria.
Although the art of rigging may be traced to prehistoric times, it was the Greeks who first invented the winch and pulley hoist that lead to a widespread replacement of ramps as the main means of vertical motion.
Greek temples of the classical age like the Parthenon featured stone blocks weighing less than 15 to 20 tons. And, the practice of erecting large monolithic columns was practically abandoned in favor of using several column drums. Archaeologists point out that the distinctive holes appearing on the stone blocks of Greek temples—either above the center of gravity of the block, or in pairs equidistant from a point over the center of gravity— are positive evidence of the existence of a mechanical lifting machine.
The first recorded evidence for the existence of the compound pulley system appears in the Mechanical Problems, attributed to Aristotle (382–322 BC). The Romans adopted the Greek crane and developed it further— enabling the construction of buildings having enormous dimensions. Several extensive recorded accounts, as well as particularly detailed reliefs of Roman cranes, exist from the late first century AD.
The art of rigging has developed to the degree that today manufacturers build 200- to 400-ton traveling cranes for power plants; hammerhead cranes of even greater capacity for shipyards; and mobile cranes and derricks capable of handling trusses and girders weighing up to 200 tons for buildings or bridges.
This handbook, however, does not deal with rigging operations of such magnitude. Rather, it covers conventional rigging operations on construction sites for erection and demolition of buildings and structures; in industrial factories, and electric power plant; in the transporting and handling of heavy machinery; as well as for mining and port facilities operations.
Included, also, is a section on the erection of temporary scaffolding used for painting, construction, repair, or demolition of buildings and structures (towers and chimneys). In the period up to 1916, the majority of scaffolding was constructed from timber. The shortages and costs of imported timber in Great Britain at the time of World War I spurred the development of new systems.
The first major development took place in 1918 when British engineers patented the universal coupler for use on steel tubes, providing many advantages over timber not only in strength and stiffness, but also in extensive reuse—as well as the obvious relative speed by which it could be assembled compared to timber scaffolding.
During that period, many different scaffolding systems were being developed around the world, consisting of welded frames that could be slotted or clipped together to form access or support towers, resulting in reduced construction time and complexity, and requiring less skill in assembly. Continual developments have resulted in stronger systems that incorporate either horizontal restraints (using lasers, ties, or braces) at more levels; or stronger tubes or connections—making scaffolding systems even easier to use. The handbook’s appendices include a bibliography, as well as government agency and industry association information resources.
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